1. Field of the Invention
The present invention relates generally to the field of frequency detectors and more particularly to programmable frequency detector circuit for determining if the frequency of an input signal is above, below, or within a programmable tolerance of a programmable frequency.
2. Description of the Prior Art
In modern electronics systems, many times it is necessary to test the output of certain tone generator or oscillator circuits to determine if the frequency is above, below, or within a given tolerance range of a predetermined frequency.
A preliminary novelty search revealed the following patents to which reference may be made to ascertain the prior art; U.S. Pat. Nos. 3,537,001, 3,566,263, 3,614,619, 3,696,293, and 3,737,789.
Many circuit configurations have been devised to compare various input frequencies relative to each other and internal standards with an output indicating the deviation between the inputs and internally generated signals. Further, other circuit configurations have been utilized to filter out undesired frequencies by passing only those frequencies within the pass-band about the desired frequency. However none of the prior art circuit configurations provide a simple and economical method of determining if the frequency of an input signal is above, below, or within a programmable tolerance of a programmable frequency during a calculation time period.